1. Field of the Invention
The present invention relates to a device for transporting objects on carrier frames, to a method of conveying for the practical application of said device and to the corresponding installation for treatment of objects.
2. Description of the Prior Art
The type of device in accordance with the invention is primarily intended to be employed for transporting parts to be subjected to a surface treatment within treatment tanks. A particular application which can be mentioned by way of non-limitative example is the painting of motor vehicles.
There already exist conveying devices having laterally spaced tracks for displacement of rigid-frame rockers or U-shaped cradles which are placed transversely to the direction of displacement of objects. These rockers or cradles serve to support carrier frames on which objects are placed and which are rigidly fixed to said rockers or cradles by suitable means. In devices of this type, the two tracks are connected to each other by means of the rigid rockers or cradles. For the return travel of these rockers or cradles, it is consequently necessary to provide a second device which is parallel to the first and operates on the same principle but in the opposite direction with two similar tracks. This entails the need for particularly complex installations which take up considerable space, thus resulting in high construction and operating costs. The same complexity is again involved in the transfer systems which are provided at both ends of the circuit in order to move the rockers from the treatment chain to the chain for returning empty rockers. At this location, the rigid frameworks of the rockers (or of equivalent cradles) entails the need for long radii of curvature. Moreover, the rigid rockers (and also the cradles) do not make it possible to approach guide ramps having steep slopes at the entrance and at the exit of tanks for the treatment of objects whereas an increase in the angle of slope of such ramps would permit a reduction in length of the treatment circuits, with even more appreciable advantages arising from the fact that the treatment operation is usually performed in a tunnel.